Deep-Ocean trenches narrow and deep trenches that are usually found next to continental margins or next to volcanic islands, especially on the pacific. The water temperature around deep oceanic trenches are usually very low, normally ranging from 0 – 2 Degrees (Celsius). At the moment the deepest oceanic trenches are the challenger in the Mariana trench, measure to be about 11,022 meters (26,163) deep. Even though, this is the deepest trench, we can find marine life, mollusks are the most common type of marine life found in the deep ocean trenches. Most of the deep ocean trenches are found in the pacific ocean, with at least 6 trenches that are deeper than 10,000. Meters. Even though deep ocean trenches represents only a very small portion of the ocean floor, they are nevertheless significant geologic features. Trenches are sites of plate convergence where slabs of oceanic lithosphere subduct and plunge back into the mantle.(Tarbuck, Lutgens, Tasa, 2012) The deep ocean trenches are formed on subduction zones. This places is where two lithospheric plates usually converge and collide, usually the one with the biggest density goes underneath the other. As a result, it creates a great depression on the marine floor. Such subduction zones are associated with an intense seismic activity that provokes tensions and friction between the two plates. Most of the tsunamis and earthquakes are caused by this phenomena. A good example of an ocean trench is the pacific margin of South America.
Asthenosphere: typical island arc features.
As mentioned on an article on the encyclopedia Britannica Deep-Ocean Trenches are “generally lie seaward of and parallel to adjacent island arcs or mountain ranges of the continental margins. They are closely associated with and found in subduction zones—that is, locations where a lithospheric plate bearing oceanic crust slides down into the upper mantle under the force of gravity. The result is a topographic depression where the oceanic plate comes in contact with the overriding plate, which may be either oceanic or continental. If the overriding plate is oceanic, an island arc develops. The trench forms an arc in plain view, and islands with explosive volcanoes develop on the overriding plate. If the overriding plate is continental, a marginal trench forms where the topographic depression appears to follow the outline of the continental margin. Explosive volcanoes are found there too.”
Plate boundary: relation to volcanoes
Accordingly to the encyclopedia Britannica “It is important to note that some seafloor features bear the name trench and are deep linear troughs; however, they do not occur in subduction zones. The Vema Trench on the Mid-Indian Ridge is a fracture zone. The Vityaz Trench northwest of Fiji is an aseismic (inactive) feature of unknown origin. The Diamantina trench (Diamantina Fracture Zone) extends westward from the southwest coast of Australia. It is a rift valley that was formed when Australia separated from Antarctica between 60 and 50 million years ago.”
Mariana Arc
Data provide significant signs about the beginning of trenches. No irregularities in the movement of internal Earth heat or variation in the Earth magnetic field happen at the trenches. Understanding of gravity records is authenticated by seismological studies. All trenches are related with zones of earthquakes centers. The sinking of oceanic lithosphere supports the relation of shortage of sediment that has accumulated within the trenches. We can say that small amount of brown and red clay, siliceous organic remains, and volcanic ash helped to form the trenches walls.
Deep-Ocean trenches narrow and deep trenches that are usually found next to continental margins or next to volcanic islands, especially on the pacific. The water temperature around deep oceanic trenches are usually very low, normally ranging from 0 – 2 Degrees (Celsius). At the moment the deepest oceanic trenches are the challenger in the Mariana trench, measure to be about 11,022 meters (26,163) deep. Even though, this is the deepest trench, we can find marine life, mollusks are the most common type of marine life found in the deep ocean trenches. Most of the deep ocean trenches are found in the pacific ocean, with at least 6 trenches that are deeper than 10,000. Meters.
Even though deep ocean trenches represents only a very small portion of the ocean floor, they are nevertheless significant geologic features. Trenches are sites of plate convergence where slabs of oceanic lithosphere subduct and plunge back into the mantle.(Tarbuck, Lutgens, Tasa, 2012)
The deep ocean trenches are formed on subduction zones. This places is where two lithospheric plates usually converge and collide, usually the one with the biggest density goes underneath the other. As a result, it creates a great depression on the marine floor. Such subduction zones are associated with an intense seismic activity that provokes tensions and friction between the two plates. Most of the tsunamis and earthquakes are caused by this phenomena. A good example of an ocean trench is the pacific margin of South America.
As mentioned on an article on the encyclopedia Britannica Deep-Ocean Trenches are “generally lie seaward of and parallel to adjacent island arcs or mountain ranges of the continental margins. They are closely associated with and found in subduction zones—that is, locations where a lithospheric plate bearing oceanic crust slides down into the upper mantle under the force of gravity. The result is a topographic depression where the oceanic plate comes in contact with the overriding plate, which may be either oceanic or continental. If the overriding plate is oceanic, an island arc develops. The trench forms an arc in plain view, and islands with explosive volcanoes develop on the overriding plate. If the overriding plate is continental, a marginal trench forms where the topographic depression appears to follow the outline of the continental margin. Explosive volcanoes are found there too.”
Accordingly to the encyclopedia Britannica “It is important to note that some seafloor features bear the name trench and are deep linear troughs; however, they do not occur in subduction zones. The Vema Trench on the Mid-Indian Ridge is a fracture zone. The Vityaz Trench northwest of Fiji is an aseismic (inactive) feature of unknown origin. The Diamantina trench (Diamantina Fracture Zone) extends westward from the southwest coast of Australia. It is a rift valley that was formed when Australia separated from Antarctica between 60 and 50 million years ago.”
Data provide significant signs about the beginning of trenches. No irregularities in the movement of internal Earth heat or variation in the Earth magnetic field happen at the trenches. Understanding of gravity records is authenticated by seismological studies. All trenches are related with zones of earthquakes centers. The sinking of oceanic lithosphere supports the relation of shortage of sediment that has accumulated within the trenches. We can say that small amount of brown and red clay, siliceous organic remains, and volcanic ash helped to form the trenches walls.
References
Deep-sea trench. (2013). In Encyclopedia Britannica. Retrieved from http://libproxy.atlantic.edu:2108/EBchecked/topic/155513/deep-sea-trench
Ocean Trenches. (2003). In K. L. Lerner & B. W. Lerner (Eds.), World of Earth Science (Vol. 2, p. 408). Detroit: Gale. Retrieved from http://go.galegroup.com/ps/i.do?id=GALE%7CCX3437800425&v=2.1&u=mays40776&it=r&p=GVRL&sw=w&asid=b223b2589119c220482319771212d158
Asthenosphere: typical island arc features. [Art]. In Encyclopedia Britannica. Retrieved from http://libproxy.atlantic.edu:2108/EBchecked/media/126187/Features-of-a-typical-island-arc
Plate boundary: relation to volcanoes. [Art]. In Encyclopedia Britannica. Retrieved from http://libproxy.atlantic.edu:2108/EBchecked/media/3266/Volcanic-activity-and-the-Earths-tectonic-plates-Stratovolcanoes-tend-to
Mariana Arc. [Photograph]. In Encyclopedia Britannica. Retrieved from http://libproxy.atlantic.edu:2108/EBchecked/media/170133/Cross-section-of-the-Mariana-Arc-showing-the-Mariana-Trench
Formation of the Mariana Trench. (2009) YouTube. Retrive November 1, 2013 from https://www.youtube.com/watch?v=BYjyGfRp3F4